Fast Idle



Ok I got an 80cc Chinese kit. I've ran it for a few weeks and it idles way too high. I've got the idle screw all the way out. **** I've even tried taking the idle screw out and I still can't seem to get the thing to idle decently... so I feather the kill switch a lot.

Can anyone offer advice to get this thing idling slower? Thanks.


Hmm, here goes my guess.
If you remove your air filter cover and look inside the throat of your high up is your brass slide (the round barrel slide that your throttle cable connects to)?
About 1 - 1 1/2 years ago, NT (stock carbs with happy time engines) had a serious issue with the barrel slides sticking in the carb. They were not machined or polished enough and would not slide easily...they ended up getting stuck and creating a serious problem.
If your kit is your seller. He/she should give you a replacement, as they probably know about the problem.
If you don't want to wait on a replacement you could remove the brass barrel and polish it down with some emery cloth...just make sure that it is perfectly clean when you put it back in the carb, and that it will slide up and down without any force at all. You should be able to drop it in there and as long as the pin is lined up it should fall right to the bottom and you should be able to tip the carb and have the barrel fall out again.
When it slides that easily your polishing is done.
The only other thing that i can think of would be that your float valve is stuck, or you have your engine installed so you carb is sitting on one heck of an angle. Either of those thoughts are likely to cause the carb to keep dumping fuel into the engine. Correcting that should be relatively easy, and I'm sure that there is a post on the forum somewhere for carb issues.

Take care, and ride safe.


I did this too. I agree with Chris, chech and make sure your slide is in correctly see this photo

Once that is proper, You can adjust the cable ends. Use the adjustment on top of the carb where the cable goes in and also at the throttle handle. As you can see the cable adjusters on my first build were all the way in. The cable was loose because I had the slide in wrong. I ended up breaking the cable(wasn't an MBc memebr yet). Also have you played with that clip on the needle? Seems best to leave it alone.
Hope this helps.

All that to say. I get really excited when I find a question I have learned the answer to. In all honesty this question has been asked many times and this will be a duplicate thread making the search feature more cloudy. Next time lets use the search to find a similar thread and go from there, if no solution is found then we can ask the question. Admin might want to move this into an existing thread.


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Thanks for the replies - you guys are right I should have used the search function first - I'll be sure to search first next time.

I'm going to take the carb apart in a couple days when I have the time and use some emory paper to smooth the slide a bit. I'm almost 100% positive that is the problem. I'll also look at making sure the throttle cable is properly adjusted. Thanks for the suggestions, and again, sorry for not searching first.


Be carefull BEFORE u use emery paper(or any other abrasives) to sand the carby slide.
My slide is teflon coated to reduce friction and give longer life so any abrasive action will do more harm than good and void your warranty.
Try other things first that were mentioned here....good luck.


ok I'll do that. Thinking about pulling the carb tonight since I have a little spare time now.

Bean Oil

Also check to be sure that your throttle cable is not too tight... that would keep the carb slide too high in it's travel, creating the too fast idle.